Victoria in December 2007A warm and generally wet month

Summary

December was a generally warm month in Victoria, both by day and night, and also saw above-normal rainfall over much of the state. Maximum temperatures averaged 1.70°C above normal over the state (9th highest on record), whilst minimum temperatures averaged 1.23°C above normal (8th highest on record). Statewide average rainfall was 33% above normal (22nd highest on record), the second successive wet month after a dry winter and early spring.

Details

Rainfall

Rainfall was above normal in most parts of the state, with the bulk of the rain falling in association with a low-pressure system which approached and then crossed the state between 19 and 23 December. Most areas north of the Divide, except for the northern Mallee, had rainfall 50% to 100% above normal, with some areas between Bendigo and Kerang receiving more than double their December average. Other areas which were more than 50% above normal included the Grampians, and Melbourne’s southern and eastern suburbs. In contrast, most of Gippsland was slightly drier than normal,
as were parts of the northern Mallee and the south-west coast west of Port Fairy, but only a few areas were more than 20% below normal.

The highest monthly total was 219.2 mm at Mount Hotham, and the highest daily total was 125.0 mm on 22 December at Stump Hill, north-west of Mansfield.
The lowest monthly total was 17.1 mm at Werrimull.

Temperature

Maximum temperature

Maximum temperatures were above average throughout the state. The month was consistently warm (except during the 19−23 December rain event), although without major extremes, until the last few days, when a major heatwave affected most of the state. Monthly averages were 2 to 3°C above normal over most of southern Victoria from West Gippsland westwards, as well as in the Wimmera, whilst they were 1 to 2°C above normal in most of
northern Victoria. In most of Gippsland and the far northeast they were less than 1°C above normal.

Minimum temperature

Minimum temperatures were also above normal statewide, with a marked lack of cold nights. They were between 1 and 2°C above normal over most of northern Victoria (locally more than 2°C along the Murray east of Albury-Wodonga), as well as around Melbourne and in most of Gippsland.
They were between normal and 1°C above normal in south-western Victoria and the Wimmera.

Wind

The strongest wind gusts in Victoria during December occurred in association with the low pressure system of 19−23 December. 135 km/h was observed at Wilsons Promontory on 22 December,
and a number of other stations (mostly elevated) exceeded 100 km/h between 21 and 23 December.

Notes

This statement has been prepared based on information available at
11 am on Wednesday 2 January 2008.
Some checks have been made on the data, but it is possible that results will change
as new information becomes available.

Normals are long-term means based on observations from
the years 1961 to 1990.
They are not shown for sites with less than 20 years of record in that time, as they cannot then be calculated reliably.
The median
is sometimes more representative than the
mean
of "normal" rain.

The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
decile ranking
(very low rainfall is in decile 1, low in decile 2 or 3,
normal in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a
percentage of the long-term mean.